I am near a University, so I see stuff like this every so often. With the excpetion of 'free-speech zones', I haven't heard of any arrests for wearing t-shirts.
Wear a shirt with the level of profanity visible on some of those shirts and there's places in Oklahoma where I guarantee you'd get arrested walking down the street. Might not stick but you'd get a free ride to the local cop shop and probably a lecture while there about public decency, provoking words and phrases, etc etc.
Edited to add:There was a time when I was younger that the mere thought of something like that happening would have gotten me mad enough to spit nails.
Now - well - not so much. I've learned - albeit slowly - over my many years that there's reasons for most rules regarding public decency, when you can have sex and with whom, the difference between free speech and just being profane and/or annoying. The list goes on.
We've tossed out of our culture a lot of the brakes on certain behaviours that kept society running relatively smoothly.
Or - maybe - just maybe - my attitude is a function of my getting old because I seem to remember my granddad saying something similar to me way back in the early 60's.